JP2011187414A - Manufacturing method for membrane-electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a membrane-electrode assembly, capable of preventing generation of cracks on an electrolyte membrane at electrode transfer. <P>SOLUTION: A CNT electrode 24 wherein CNTs are vertically arranged on the surface of a CNT substrate 16 is formed on the CNT substrate 16. The CNT electrode 24 is transferred to an electrolyte membrane 26, after the CNT substrate 16 is arranged on an opening of a spacer jig 14; and furthermore, a masking jig 18 is arranged so as to cover a peripheral edge of the CNT substrate 16. Consequently, a substrate edge can be restrained from coming into contact with the electrolyte membrane 26 at electrode transfer, since the masking jig 18 can cover the substrate edge of the CNT substrate at the electrode transfer. Generation of cracks on the electrolyte membrane 26 can be restrained, without fail, at the time of the electrode transcription if restraining contact with the electrolyte membrane 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a membrane electrode assembly, and more particularly, to a method for manufacturing a membrane electrode assembly in which an electrode is constituted by carbon nanotubes.

  Conventionally, for example, in Patent Document 1, when an electrode and an electrolyte membrane having a larger dimension are joined, the center portion of the electrolyte membrane is sandwiched between a pair of electrodes, and at the same time, the electrolyte membrane outside the electrode range is placed in the center. A method of manufacturing a membrane electrode assembly (hereinafter also referred to as MEA) by sandwiching a pair of elastic bodies with openings and pressing the electrodes while heating is disclosed. When an electrolyte membrane larger than the electrode is used, wrinkles may occur in the electrolyte membrane outside the electrode range due to drying shrinkage of the electrolyte membrane during pressing. Therefore, by heating the electrode and pressing the electrolyte membrane outside the electrode range while being sandwiched between the elastic bodies with openings, the electrolyte membrane outside the electrode range can be joined while being restrained. Therefore, it is possible to manufacture a membrane electrode assembly in which the generation of wrinkles is suppressed.

Japanese Patent Laid-Open No. 2004-214001 JP 2002-260684 A JP 2007-172844 A

  By the way, MEA is generally manufactured by transferring an electrode formed on a substrate such as a PTFE sheet or a metal plate to the electrolyte membrane side. Also in the said patent document 1, after forming an electrode on a base material, it cuts out with a base material and is transcribe | transferred to the electrolyte membrane side.

  On the other hand, the electrolyte membrane on the transfer side is generally as thin as about 5 to 20 μm. In addition, the electrolyte membrane is heated above the glass transition point of the electrolyte membrane material during transfer. Therefore, it can be said that the mechanical strength of the electrolyte membrane is extremely low during transfer. Further, at the time of transfer, a transfer pressure of 3 to 10 MPa is applied between the electrolyte membrane and the base material for the purpose of preventing peeling after transfer.

  Therefore, when the electrode with the substrate attached is transferred, the surface of the electrolyte membrane may come into contact with the edge of the substrate. When the surface of the electrolyte membrane comes into contact with the edge of the base material, there is a possibility that a local stress is applied to cause a partial crack. In particular, as in Patent Document 1, when the electrode is cut out together with the base material, the transfer side edge is sharp. Therefore, when contacting a sharp edge, the electrolyte membrane may be cut.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a membrane electrode assembly capable of preventing the occurrence of cracks in the electrolyte membrane during electrode transfer.

In order to achieve the above object, a first invention is a method of manufacturing a membrane electrode assembly,
A base material having an electrode formed on the surface and a spacer jig having an opening having a size larger than that of the base material are prepared, and the base is formed so that the outer periphery of the base material is surrounded by the opening of the spacer jig. Arranging the material and the spacer jig;
A masking jig having an opening having a size smaller than that of the substrate is prepared, and the opening of the masking jig is opposed to the electrode forming surface of the substrate, and the non-opening of the masking jig is set to the base. A step of covering the periphery of the material;
Placing an electrolyte membrane larger than the electrode formation surface so as to cover the opening of the masking jig;
Preparing a transfer pressure applying plate having a size smaller than the opening of the masking jig, and arranging the plate so as to face the opening of the masking jig through the electrolyte membrane;
Arranging an elastic body so as to surround the outer periphery of the transfer pressure applying plate;
It is characterized by providing.

The second invention is the first invention, wherein
The periphery of the opening of the masking jig on the side in contact with the electrolyte membrane is chamfered so as to be rounded.

The third invention is the first or second invention, wherein
The spacer jig is thicker than the base material, and the periphery of the opening of the spacer jig on the side in contact with the non-opening of the masking jig is chamfered to be rounded. .

The fourth invention is the invention according to any one of the first to third inventions,
The electrode comprises carbon nanotubes;
The carbon nanotube is formed perpendicular to the surface direction of the substrate.

  According to the first invention, a spacer jig having an opening having a size larger than that of the substrate on which the electrode is formed and a masking jig having an opening having a size smaller than that of the substrate are used. The base material is installed in the opening of the jig, and is installed on the spacer jig so as to cover the periphery of the base material with the non-opening part of the masking jig. An electrolyte membrane larger than the electrode forming surface can be arranged and transferred. Therefore, since the edge of the base material can be covered with the masking jig, the electrolyte membrane outside the electrode range can be transferred without contacting the edge of the base material.

  Further, transfer can be performed using a transfer pressure applying plate having a size smaller than the opening of the masking jig and an elastic body arranged so as to surround the outer periphery of the transfer pressure applying plate. Therefore, the electrolyte membrane outside the electrode range can be sandwiched and transferred between the non-opening portion of the masking jig and the elastic body. As described above, according to the first invention, it is possible to simultaneously prevent the generation of film wrinkles and the generation of film cracks due to the substrate edge.

  At the time of transfer, the electrolyte membrane larger than the electrode formation surface contacts not only the electrode but also the masking jig. Therefore, there is a possibility that a film crack may occur due to the edge of the masking jig. According to the second invention, since the periphery of the opening of the masking jig on the side in contact with the electrolyte membrane is chamfered to be rounded, the occurrence of film cracks due to the edge of the masking jig can be prevented.

  According to the third invention, the spacer jig is thicker than the base material, and the periphery of the opening of the spacer jig on the side in contact with the non-opening of the masking jig is rounded. Since it is chamfered, it can be transferred while being inclined toward the opening side of the masking jig. Therefore, the outer peripheral contact portion of the transfer pressure applying plate which is easily loaded can be transferred gently.

  According to the fourth invention, an electrode including carbon nanotubes formed perpendicular to the surface direction of the substrate can be transferred to the electrolyte membrane without causing cracks in the electrolyte membrane.

It is a figure for demonstrating the MEA manufacturing apparatus used for the manufacturing method of MEA of this embodiment. It is process drawing of the manufacturing method of MEA of this embodiment. It is an expansion schematic diagram of the CNT board | substrate 16 in which the CNT electrode 24 was formed. It is a figure for demonstrating the effect by the manufacturing method of this embodiment. It is a figure for demonstrating the specific example of the manufacturing method of MEA of this embodiment. It is a figure for demonstrating the comparative example of the manufacturing method of MEA of this embodiment.

Hereinafter, the manufacturing method of the MEA of this embodiment will be described with reference to FIGS.
First, the MEA manufacturing apparatus used for the MEA manufacturing method of this embodiment will be described with reference to FIG. The MEA manufacturing apparatus used in the MEA manufacturing method of the present embodiment includes hot press plates 10 and 12. Each of the hot press plates 10 and 12 is made of a metal having a high thermal conductivity. Each of the hot press plates 10 and 12 includes a heater or the like (not shown) and is configured to be heatable. Each of the hot press plates 10 and 12 is connected to a lifting device (not shown) and is configured to be liftable.

  A spacer jig 14 is provided on the hot press plate 10. The spacer jig 14 is made of a substrate made of metal, ceramics, silicon, or polytetrafluoroethylene (PTFE), and a CNT substrate 16 as a carbon nanotube (hereinafter also referred to as CNT) growth substrate is provided at the center thereof. An opening 14a larger than the size of is formed. The spacer jig 14 is formed thicker than the CNT substrate 16. Further, as shown in FIG. 1, the upper corner 14b of the spacer jig 14 is rounded and chamfered.

  A masking jig 18 is provided on the spacer jig 14. The masking jig 18 is made of a PTFE sheet, and an opening 18a smaller than the size of the CNT substrate 16 is formed at the center thereof. Further, the upper corner 18 b of the masking jig 18 is chamfered round like the spacer jig 14.

  Above the masking jig 18, a transfer pressure applying plate 20 and a film wrinkle preventing elastic body 22 are provided. The transfer pressure applying plate 20 is made of a rigid body such as PTFE or metal, and is made smaller than the size of the opening 18a. The membrane wrinkle prevention elastic body 22 is made of a sheet made of polyimide or PTFE containing a cushion material therein, and an opening 22a larger than the size of the membrane wrinkle prevention elastic body 22 is formed at the center thereof. . The thickness of the transfer pressure applying plate 20 is determined by the correlation with the thickness of the film wrinkle preventing elastic body 22, the crushing allowance, and the compression deformation characteristics.

Next, the details of the MEA manufacturing method of the present embodiment will be described using FIGS. 2 to 4 as appropriate.
FIG. 2 is a process diagram of the MEA manufacturing method of the present embodiment. As shown in FIG. 2 (1), in this embodiment, first, the CNT substrate 16 having the CNT electrode 24 formed on the surface is installed in the opening 14 a of the spacer jig 14.

  Here, the CNT electrode 24 will be briefly described with reference to FIG. FIG. 3 is an enlarged schematic view of the CNT substrate 16 on which the CNT electrodes 24 are formed. As shown in FIG. 3, the CNT electrode 24 includes a plurality of CNTs 24a. The CNT 24a is grown by supplying a carbon source gas to the seed catalyst under a high temperature condition of about 800 ° C. starting from a seed catalyst (not shown) supported on the surface of the CNT substrate 16. It is formed perpendicular to the surface direction of the substrate 16. Catalyst particles 24b are provided on the outer surface of each CNT 24a. An ionomer 24c is provided on the outer surface of each CNT 24a so as to cover the catalyst particles 24b. A gap 24d is formed between adjacent ionomers 24c.

  Returning to FIG. 2 again, the details of the MEA manufacturing method of this embodiment will be described. After the CNT substrate 16 is installed in (1) of FIG. 2, the periphery of the CNT substrate 16 is covered while the CNT electrode 24 and the opening 18a of the masking jig 18 are opposed to each other as shown in (2) of FIG. Thus, the masking jig 18 is installed. Subsequently, as shown in FIG. 3 (3), an electrolyte membrane 26 is installed on the masking jig 18 so as to cover the opening 18 a of the masking jig 18.

  After the electrolyte membrane 26 is installed, the transfer pressure applying plate 20 is installed on the electrolyte membrane 26 so as to face the opening 18a of the masking jig 18 as shown in FIG. At the same time, the film wrinkle prevention elastic body 22 is installed so as to surround the outer periphery of the transfer pressure applying plate 20. Subsequently, as shown in FIG. 5 (5), the heat press plate 12 is installed on the transfer pressure applying plate 20 and the film wrinkle prevention elastic body 22, and these are pressed vertically while the heat press plates 10 and 12 are heated. Move in the direction and pressurize. Thereafter, by removing the CNT substrate 16, an MEA in which the CNTs 24a are formed perpendicular to the surface direction of the electrolyte membrane 26 can be manufactured.

  Since the CNTs 24a are formed perpendicular to the surface direction of the electrolyte membrane 26, the gap 24d described with reference to FIG. 3 can be used as a gas flow path or a drainage path for water generated by an electrochemical reaction. Therefore, if the MEA in which the CNTs 24a are formed perpendicular to the surface direction of the electrolyte membrane 26 is used in the fuel cell, the catalyst particles 24b in the vicinity of the electrolyte membrane 26 can be used effectively. If the catalyst particles 24b can be used effectively, the catalyst can be reduced and the cost can be reduced accordingly.

  In order to manufacture such an MEA, it is necessary to transfer the CNTs 24 a perpendicular to the surface direction of the electrolyte membrane 26. In order to transfer vertically, it is desirable to use the CNT electrode 24 without peeling from the CNT substrate 16. This is because when the CNT electrode 24 is peeled from the CNT substrate 16, it is difficult to handle, and the orientation of the CNT 24 a is likely to deteriorate during transfer.

  However, a substrate such as silicon, quartz, or SUS is used for the CNT substrate 16. The CNT substrate 16 is cut to a transfer size after the CNT electrode 24 is formed on the surface thereof. This is because it is effective when a portion having a good orientation of CNTs is selected and transferred from a large-area substrate. Therefore, the edge of the CNT substrate 16 cut out to the transfer size is generally sharp.

  On the other hand, the electrolyte membrane 26 is generally as thin as about 5 to 20 μm and is heated to a temperature higher than the glass transition point of the polymer material constituting the electrolyte membrane 26 during transfer. Therefore, the mechanical strength of the electrolyte membrane 26 during transfer is extremely low. Further, at the time of transfer, a transfer pressure of 3 to 10 MPa is applied between the electrolyte membrane 26 and the CNT substrate 16 so that peeling does not occur thereafter. Furthermore, the thickness of the CNT electrode 24 is generally about 30 μm. Therefore, when the CNT substrate 16 is used without being peeled off, the edge of the CNT substrate 16 comes into contact with the electrolyte membrane 26, and as a result of receiving a local stress, the electrolyte membrane 26 may be cracked.

  If the edge of the CNT substrate 16 is chamfered, the occurrence of cracks in the electrolyte membrane 26 can be suppressed. There are two possible timings for chamfering. For example, when the CNT substrate 16 is individually produced and the CNT 16a is grown, the chamfering can be performed before the CNT growth. However, the method of chamfering at this timing is not economical because it is not suitable for mass production. On the other hand, when chamfering is performed after the formation of the CNT electrode 24, it is possible to cope with a case where a portion having a good state is selected from a large area substrate and divided into small areas. However, the method of chamfering at this timing has a problem of contamination due to the substrate material of the CNT substrate 16. Therefore, it is not always appropriate to employ the chamfering process, and it can be said that transfer without chamfering process is desirable.

  As another method that can suppress the occurrence of cracks in the electrolyte membrane 26, a method in which the CNT substrate 16 is made wider than the formation region of the CNT electrode 24 is also conceivable. That is, if a blank portion where the CNT electrode 24 is not formed is provided on the peripheral edge of the CNT substrate 16 and an elastic body having a function similar to the masking jig 18 is placed and transferred on the blank portion, for example, the electrolyte membrane There is a high possibility that the occurrence of 26 cracks can be suppressed. However, a sufficient space capable of supporting the elastic body is also required for the blank portion. Therefore, it is not economical when an expensive CNT substrate 16 is used.

  Another method is to increase the thickness of the spacer jig 14. That is, if the spacer jig 14 is thickened under the condition that the transfer pressure is not changed, the contact of the electrolyte film 26 with the edge of the CNT substrate 16 can be eased, so that there is a possibility that the occurrence of cracks in the electrolyte film 26 can be suppressed. high. However, if the spacer jig 14 is thickened, the height difference between the electrolyte membrane 26 and the CNT electrode 24 increases accordingly, and thus the electrolyte membrane 26 may be wrinkled when the transfer pressure applying plate 20 is pushed in. End up.

  Next, the effect by the manufacturing method of this embodiment is demonstrated using FIG. According to the MEA manufacturing method of the present embodiment, as shown in FIGS. 2A and 2B, the CNT substrate 16 is installed in the opening 14a of the spacer jig 14, and the periphery of the CNT substrate 16 is formed. A masking jig 18 is installed so as to cover it. Therefore, as shown in FIG. 4, the edge of the CNT substrate 16 can be covered with the masking jig 18, so that contact with the electrolyte membrane 26 can be suppressed. Since it can suppress that it contacts the electrolyte membrane 26, generation | occurrence | production of a crack can be suppressed reliably.

Further, as shown in FIG. 4, since the upper corner 18b of the masking jig 18 is chamfered, the occurrence of cracks in the electrolyte membrane 26 due to the edge of the masking jig 18 can be suppressed.
Further, as shown in FIG. 4, the spacer jig 14 is thicker than the CNT substrate 16, and the upper corner 14b of the spacer jig 14 is chamfered, so that the edge of the CNT substrate 16 is chamfered. Transfer while releasing local load.

  Further, as shown in FIG. 4, a film wrinkle prevention elastic body 22 is installed so as to surround the outer periphery of the transfer pressure applying plate 20. Accordingly, the electrolyte membrane 26 can be sandwiched and pressed between the masking jig 18 and the membrane wrinkle-preventing elastic body 22. Therefore, the generation of film wrinkles can be prevented.

Next, the manufacturing method of MEA of this embodiment is concretely demonstrated using FIG.5 and FIG.6.
As shown in FIG. 5, a SUS flat plate was prepared as a hot press plate, and a substrate die-cut silicon sheet (thickness 0.8 mm) was prepared as a spacer jig. In addition, a silicon substrate (thickness: about 0.65 mm) having a vertically aligned CNT electrode (thickness in the alignment direction 60 μm) formed on the surface was prepared as a CNT substrate. Also, a Teflon mask (thickness: 0.1 mm) as a masking jig (Teflon: registered trademark, DuPont), an electrolyte membrane with an anode film (fluorine electrolyte membrane, electrolyte thickness: 10 μm), and a Teflon as a transfer pressure applying plate A spacer (thickness 0.3 mm) and a cushion GDL sandwiched between kapton sheets as a film wrinkle-preventing elastic body were prepared.
Next, these are arranged as shown in FIG. 5, pre-pressurization (2 tons, 140 ° C., 10 minutes), main pressurization (25 tons, 140 ° C., 10 minutes), cooling (25 tons, ˜40 ° C.) The CNT electrode was transferred to the electrolyte membrane side.
As a result, no film wrinkle was generated, and the electrolyte membrane was not cut at the edge of the substrate. As a result, by installing a silicon die-cut substrate and further using a Teflon mask, a pressure sufficient and sufficient to prevent wrinkles is applied outside the CNT electrode range of the electrolyte membrane, but the CNT substrate edge is sharp on the electrolyte membrane. It was proved that no large local stress was applied from the part.

As shown in FIG. 6, a SUS flat plate was prepared as a hot press plate. In addition, a silicon substrate (thickness: about 0.65 mm) having a vertically aligned CNT electrode (thickness in the alignment direction 60 μm) formed on the surface was prepared as a CNT substrate. Further, a Teflon mask (thickness 0.1 mm), an electrolyte membrane with an anode film (fluorine electrolyte membrane, electrolyte thickness 10 μm), a Teflon spacer (thickness 0.05 mm), and a Teflon sheet with a cushion GDL were prepared.
Next, these were arranged as shown in FIG. 6 and transferred under the same conditions as in FIG. 5 in the order of pre-pressurization, main pressurization, and cooling. As a result, a part of the electrolyte membrane was cut as shown in FIG.

  As described above, according to the manufacturing method of the present embodiment, an electrode including CNTs formed perpendicular to the surface direction of the CNT substrate without causing cracks in the electrolyte membrane due to the edges of the CNT substrate is formed on the electrolyte membrane. Can be transferred.

  In the present embodiment, the MEA manufacturing method using the CNT substrate 16 having the CNT electrode 24 formed on the surface has been described. However, the manufacturing method using a general carbon electrode that does not use the vertically aligned CNT is also used. Applicable. Even when a general carbon electrode is used, when the carbon electrode is formed on a substrate such as that used for the CNT substrate 16 and cut out together with the substrate and transferred to the electrolyte membrane, the edge becomes sharp due to the cutting out. It is.

DESCRIPTION OF SYMBOLS 10, 12 Hot press board 14 Spacer jig 14a, 18a, 22a Opening part 14b, 18b Corner | angular part 16 CNT board | substrate 18 Masking jig | tool 20 Transfer pressure provision board 22 Prevention elastic body 24 CNT electrode 26 Electrolyte membrane

Claims (4)

A base material having an electrode formed on the surface and a spacer jig having an opening having a size larger than that of the base material are prepared, and the base is formed so that the outer periphery of the base material is surrounded by the opening of the spacer jig. Arranging the material and the spacer jig;
A masking jig having an opening having a size smaller than that of the substrate is prepared, and the opening of the masking jig is opposed to the electrode forming surface of the substrate, and the non-opening of the masking jig is set to the base. A step of covering the periphery of the material;
Placing an electrolyte membrane larger than the electrode formation surface so as to cover the opening of the masking jig;
Preparing a transfer pressure applying plate having a size smaller than the opening of the masking jig, and arranging the plate so as to face the opening of the masking jig through the electrolyte membrane;
Arranging an elastic body so as to surround the outer periphery of the transfer pressure applying plate;
A method for producing a membrane electrode assembly, comprising:   The method for manufacturing a membrane electrode assembly according to claim 1, wherein the periphery of the opening of the masking jig on the side in contact with the electrolyte membrane is chamfered so as to be rounded.   The spacer jig is thicker than the base material, and the periphery of the opening of the spacer jig on the side in contact with the non-opening of the masking jig is chamfered to be rounded. The manufacturing method of the membrane electrode assembly of Claim 1 or 2. The electrode comprises carbon nanotubes;
The method for producing a membrane electrode assembly according to any one of claims 1 to 3, wherein the carbon nanotubes are formed perpendicular to the surface direction of the base material.

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